The discharge of dental waste water into the public sewer system is undergoing re-evaluation in the Great Lakes Region. The Great Lakes Water Quality Guidance criteria for wildlife protection was established at 1300 pg/L mercury. As this criteria is implemented, local Public Works Units will be working to determine the most efficient means of compliance. The preferred approach is to have the mercury removed before it enters the sewer system. With this thought as the driving force, there is the possibility that some form of amalgam recycling or utilization of amalgam separators will be mandated eventually for the small generator dental offices. The intent of this project is to evaluate the efficiency of such amalgam separators. Specifically two aims will be investigated: A1: Determine the efficiency of amalgam separators with respect to particle removal. The hypothesis to be tested is that the amalgam separators will reduce the number of particles, but that particle removal does not necessitate mercury removal. The experiment will utilize waste water samples to determine particle size and distribution before and after passing through the amalgam separators. A2: Determine the efficiency of amalgam separators with respect to mercury removal. The hypothesis is that since the amalgam separator is a centrifugal separator device, the process of removal will break the particles down into smaller sizes and increase the amount of mercury that is soluble. Our findings indicate that the soluble portion of the dental waste water stream should be considered as the critical parameter for assessing the impact of dental waste water stream on the mercury load of waste water treatment facilities, as well as for designing removal alternatives at the source. Total mercury will be evaluated by using cold vapor atomic absorption of the supernatant before and after passing through the amalgam separator.